Tensile Strength (TS)
Elongation is the length of the material at breaking point and is indicated as the percentage of its initial length. For instance, if an elastomer reaches twice its original length before breaking, the elongation would be indicated as 100%.
An elastomer can be qualified mechanically by measuring the force that takes the rubber sample to its rupture point. The elongation for elastomers needs to be determined to choose the best option.
Since elongating a rubber sample leads to deformation, it is important to know, as the sample gets stretched, certain sections will start reducing and eventually tear.
The test can determine the variability in elastomer vulcanizates and parameters influencing the stress-strain properties like preconditioning of rubber, temperature, and relative humidity.
A traction device, known as the dynamometer can be used to measure the size of the rubber sample during extension, and when the breaking point occurs.
O-ring rubber samples are rotated during extension to ensure specific zones remain unaffected.
When gauge marks are used to determine specific test sections, only the length is used for calculation. The distance between the grips is also used as the original gauge length.
As stated above, the elongation is indicated in the form of percentage and is indicated as two significant figures.
Elongation percentage = (elongation at tear) x 100/(original gauge length)